Raphael writes –

Being able to play NES and SNES games on the Wii’s Virtual Console is great (Thanks Nintendo!), but it’s much more fun to do it with the original controllers. (And some games are much more playable like this). That’s why I decided to design this Nes/Snes controller to USB conversion circuit.

Snes/Nes controller to gamecube/Wii conversion project – Link.